President Obama and Canadian Prime Minister Stephen Harper participate in a joint news conference in the Rose Garden at the White House in 2012. / Charles Dharapak, AP

by Aamer Madhani, USA TODAY

by Aamer Madhani, USA TODAY

WASHINGTON - When President Obama heads to Mexico on Wednesday for talks with fellow heads of state at the North American Leadership Summit, he will almost certainly get pressured once again by Canadian Prime Minister Stephen Harper to approve the controversial Keystone XL pipeline.

The Canadians - along with a bipartisan group of U.S. lawmakers - are pressing hard on Obama to approve the controversial pipeline just weeks after the State Department issued a report finding the pipeline will have a negligible impact on climate because expanded development of carbon-heavy tar sands of northwest Canada is inevitable, with or without the pipeline.

But in the midst of all the lobbying on the pipeline, which would bring oil from Alberta to the Gulf of Mexico, there's a growing sense among Canadian officials that there won't be a final resolution on the issue until after Obama leaves office in 2017.

"We must set our priorities, tailor our agenda and make our preparations with that small window of opportunity in mind. The next one will arrive in 2017," Jim Prentice, a former Canadian Conservative Party official who has been touted as a potential successor to Harper, said in a speech in Ottawa last week.

The comments by Prentice echo sentiments expressed by Harper, who before last month's State Department report had begun to show impatience with the Obama administration over Keystone, which was first proposed when George W. Bush was in the White House.

Harper has criticized Obama for repeatedly "punting" on permitting the pipeline but has expressed confidence that approval to build the final 800 miles of the pipeline (the southern segment has already been completed) is inevitable, whether by Obama or the next U.S. president.

Obama and Harper are expected to hold a bilateral meeting during the one-day summit, which is to focus heavily on trade issues.

The summit comes as Obama faces a measure of opposition from members of his own party, including Senate Majority Leader Harry Reid and House Minority Leader Nancy Pelosi, as he seeks to fast-track finalizing the Trans-Pacific Partnership, a major trade deal of which Canada and Mexico are among 12 Pacific partners.

But in Obama's one-on-one meeting with Harper, as well as in interaction with North American business leaders and academics at the summit, the Keystone issue will loom large.

After the State Department issued its report, Harper's Conservative Party launched a web advertisement indirectly poking at Obama and opponents of the project, including billionaire and Democratic donor Tom Steyer.

"Now American billionaires are using their wealth to attack our oil industry," the ad said. "The distortion of facts and hysterical fear-mongering has to stop."

Ahead of Wednesday's summit in Toluca, the hometown of Mexico President Peña Nieto, the White House said that Obama expected to get pressed by Harper on Keystone during the meetings. But Harper shouldn't expect to hear anything new.

"I think what President Obama will do is explain to (Harper) where we are in the review of the Keystone pipeline and indicate, of course, that we will let our Canadian friends know when we've made a decision," said a senior administration official, who was not authorized to speak on the record about the upcoming summit and requested anonymity.

The State Department is now conducting a 90-day interagency review to determine whether the pipeline is in the nation's best interest. The finding will be delivered to Obama by Secretary of State John Kerry, but there is no deadline for Obama to make a decision. Obama has said that climate impact would be "absolutely critical" to whether he approves or denies the pipeline.

In Washington, the pressure from opponents and proponents of the project is expected to only increase as the interagency review nears completion.

On Monday, as Republican lawmakers took aim at the White House on the five-year anniversary of Obama's $800 billion stimulus plan that helped the American economy rebound from the Great Recession, they repeatedly pointed to Keystone as the sort of project Obama should back to help an economy that, while improved, is still sputtering along.

"We should set our sights higher and aim to restore America as a nation of builders," said House Speaker John Boehner, R-Ohio. "Whether it's improving job training, building the Keystone pipeline or expanding markets for American exports, there are a number of areas ripe for bipartisan action."